If real Trappists use primary for 5-7 days, why should I use 3 weeks

I've been reading Stan Hieronymous' "Brew Like a Monk". I was surprised to see that all of the abbeys leave all their beers in primary for only 5-7 days. There's a lot of variation in secondary, 2 days - 6 months depending on filtering, etc. etc., but the primary period is remarkably consistent. Yet all the advice I read here says to leave a biggish beer like a dubbel in primary for 10 days to 3 weeks. I brewed a dubbel last Sunday at it looks finished. If, after a couple days of hydrometer tests, that proves to be true, shouldn't I follow the monks and move it to secondary? If not, why not?

bearymore said:

shouldn't I follow the monks and move it to secondary? If not, why not?

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not too many Monks actively involved anymore.

Diacetyl? Not sure. Do you follow the same pitching rate that they do? My memory of this is a little hazy but I seem to recall listening to a basic brewing podcast and hearing something about the trappist breweries using pretty crazy pitching rates.

1. Pitching rate.
2. If it's done, it's done.

To add to what David_42 mentions, there is a podcast by Stan and in there he talks about the amounts of yeast they pitch in many of those breweries. That is a huge factor. Additionally, it's like anything; if you follow the golden rule it usually helps guarantee success, but that doesn't mean your beer can't be done fermenting in three days. It simply means 10 days is a highly accepted, tested and good amount of time for most Ales. So that is why most people go by that.

People that brew beer professionally go to a lot of trouble to control the environement and conditions under which they brew. This creates consistancy and they can judge exactly when a beer is done. At home we usually have to work with the conditions we have and those can vary greatly from brew to brew. In order to make sure the beer is done, many choose to leave it longer then may be absolutley needed just to be sure since it can't hurt and may help in the long run. If you're absolutely sure its done then move it. If not, some extra time sure can't hurt anything.

It's now been 8 days for my Westmalle Dubbel clone. OG was 1.072 and SG is now 1.016, so it's been about 76% apparent attenuation. I used White Labs WLP500 and made a 1.75 quart starter. I pitched at about 75 degrees. 4 1/2 hours later was the first time I checked the beer and it was already fermenting vigorously with a fully formed krauesen -- surprised me. Vigorous fermentation lasted only about 2 days (at 70 degrees) and intermittent bubbling for another 3, so that is consistent with the 5 days cited in the book. Being more conservative than my first post sounds, I waited until today (8 days) before taking the first SG reading.

Very tasty...